How to Store Flour Properly: Shelf Life, Containers, Freezer

White flour keeps 6 to 12 months in the pantry, whole wheat 3 to 6, and four days in the freezer kills insect eggs. Shelf life by flour type, the right container and what "best before" really means.

White flour keeps 6 to 12 months in the pantry, unopened whole wheat flour 3 to 6 months, and white flour can be frozen for indefinite storage. Those figures come from the North Dakota State University (NDSU Extension) food storage guide. The difference between the two is not the grind but the fat: whole wheat flour contains the germ and bran, and King Arthur Baking explains that the fat in the germ is exposed to oxygen during milling and starts oxidising immediately, which is why whole grain and nut flours always have a shorter shelf life than white flour.

How long each flour lasts

Rancid flour is recognised by its smell; King Arthur Baking compares it to Play-Doh. The NDSU guide gives its shelf lives on the assumption that the flour is dry and sealed. White flour does not need refrigeration, but for whole wheat flour the fridge or freezer is the only way to keep it longer than half a year.

Source: NDSU Extension, Food Storage Guide; freezer recommendation: King Arthur Baking.

The container: two layers between flour and kitchen

The paper bag protects flour while it is sealed. Once opened, King Arthur Baking advises one or two extra layers of protection, for example the bag inside a lidded container, because three things in the kitchen spoil flour: moisture, odours that pass through paper, and heat. A glass, metal or rigid plastic container with a gasket handles all three. Keep it away from the stove and dishwasher, which heat and humidify the neighbouring cupboards. The same advice applies to every dry good on that shelf: rice, pasta, oats and breadcrumbs.

Pests: four days in the freezer

Eggs of pantry moths and weevils arrive from the mill or the shop and are invisible to the naked eye. King Arthur Baking states that four days in the freezer effectively kills existing pests and their offspring. A practical routine: a new bag goes into the freezer for four days first, then into a container on the shelf. If you see web-like threads, clumps that hold together or tiny insects, discard the flour and check every open dry good in the same cupboard. There is no need to let flour warm up before baking: according to King Arthur Baking it can be used straight from the fridge or freezer.

The date on the bag is a quality date

Flour carries a "best before" date. According to the Ministry of Agriculture guide published by the Croatian agency HAPIH, that label refers to food quality, while "use by" refers to safety. Food labelled "best before" is safe to eat after the date if the storage conditions on the packaging were followed, but it may not have the same taste or texture. For flour that means: if it is dry, odourless and free of insects it can still be used after the date, best for roux, biscuits or breading, because older flour develops weaker gluten for bread. Recipes that use larger quantities of flour are in the recipes section.

Flour is a raw food

The FDA notes that the grains flour is milled from can carry Salmonella and pathogenic E. coli, and processing into flour does not kill those bacteria. Flour therefore counts as a raw ingredient: keep it separate from ready-to-eat food, wash your hands after handling it, and never taste raw dough. In the same guide the FDA asks for the refrigerator to be at 40 °F (4 °C), which is also the temperature at which whole wheat flour keeps 6 to 8 months. For the freezer, Health Canada gives −18 °C (0 °F). What flour can do in the kitchen is covered in the flour guide on the blog.

Sources

• NDSU Extension: Food Storage Guide
• King Arthur Baking: Flour storage
• FDA: Handling Flour Safely
• HAPIH: Guide to food date labelling (Croatian)